Mixed Langmuir-Blodgett Research Articles

Effect of subphase temperature on the phase-separated structures of mixed Langmuir and Langmuir–Blodgett films of fatty acids and hybrid carboxylic acids

We examined the phase-separated structures of the mixed Langmuir–Blodgett (LB) films of C k H 2 k +1COOH (H kA: k = 17, 21) and C m F 2 m +1C 10H 20COOH (F mH10A: m = 6, 8) fabricated isothermally or after isobaric thermal treatments. Under isothermal fabrication conditions, disks and wire-type domains formed in the H17A/F6H10A LB films at high and low fabrication temperatures, respectively, because the line tension and dipole–dipole interaction were comparable with each other. The thermodynamically stable phases of H21A/F6H10A LB films at high and low fabrication temperatures were disks and polygonal domains, respectively. Isobaric thermal treatments of the Langmuir films affected the domain size and not the domain shape when the transfer temperature was the same. Isobaric thermal treatments were effective in controlling the domain size. The thermodynamically stable phases of both H17A/F8H10A LB films and H21A/F8H10A LB films were nanowires in the range of the fabrication temperatures studied. Isobaric thermal treatments of the Langmuir films did not affect the domain shape significantly and affected the domain size in both the LB films studied. The change in the value m of F mH10A was more effective in controlling the phase-separated structures of the mixed LB films than the value of k of H kA.

Optical and Electrical Properties of Merocyanine Dye LB Films by Various Time of UV Irradiation and Heat Treatment

The Langmuir-Blodgett (LB) technique provides many possibilities for the control of film thickness, dimensions, and molecular structures on the nanometer scale. Various kinds of dye molecules have been found to form the J-aggregation which has been used as sensitizers of silver halide photography for long time. In recent years, they attract attention as model systems for investigating the ultra-fast exciton dynamics, materials for ultra-fast nonlinear optical devices, fluorescence probes for mitochondrial membranes. We fabricated the merocyanine dye LB films with arachidic acid (AA). In order to observe the J-aggregation of the merocyanine dye LB films, CdCl2 and KHCO3 solutions were added in subphase. From the optical absorption spectra of the mixed dye LB films (6Me-Ds:AA = 1:2) at different layers, the optical absorption peak was about 520 nm. However, the optical absorption peak of the LB films was shifted to 600 nm, when CdCl2 and KHCO3 solutions were added. This is the consequence result to the J-aggregation of the merocyanine dye. We also investigated the optical absorption peak of the LB films according to various time at 60 degrees C and 275 nm UV. We measured the STM morphology of the merocyanine dye LB film (1 layer) before UV irradiation and heat treatment. The morphology size of the LB film on HOPG was 5 nm. The roughness and molecular size were about 66.163 pm and 0.176 nm, respectively. The J-aggregation of this type was also accompanied by large morphological changes. We analyze the morphology and electrical properties of the LB films by the scanning tunneling microscopy (STM).

Monolayers and Langmuir–Blodgett films of luminescent 1,3,5-triazine derivatives containing naphthalene or anthracene chromophores

Monolayer behaviors and Langmuir–Blodgett (LB) films of three luminescent aryl triazines, 2,4,6-tri(naphthalen-1-yl)-1,3,5-triazine (TN 1Ta), 2,4,6-tri(naphthalen-2-yl)-1,3,5-triazine (TN 2Ta), and 2,4,6-tri(anthracen-9-yl)-1,3,5-triazine (TATa) have been investigated. Surface pressure-area isotherms indicated that pure aryl triazines were difficult to form stable monolayers, while their mixtures with arachidic acid (AA) could be stabilized at the air–water interface. The mixed LB films of triazine-AA were deposited on substrate surfaces and analyzed by using UV–vis and infrared absorption spectra, X-ray photoelectron spectra, as well as scanning electron microscopy. Morphologies of the LB films and molecular aggregates were closely dependent on the structure of triazines and the surface pressures of deposition. Under UV radiation, TN 1Ta and TN 2Ta emitted at 410–460 nm while TATa emitted at 500–510 nm, with the emission lifetime falling into the range of 0.29 to 10.8 ns. Compared with those in solutions, the emissions of aryl triazines were red shifted in the LB films, especially for the TN 1Ta-AA and TN 2Ta-AA, which was attributed to the closely packed arrangement for the molecules in the LB films.

Patterning of Functional Compounds by Multicomponent Langmuir−Blodgett Transfer and Subsequent Chemical Modification

The multicomponent transfer of functional molecules by Langmuir-Blodgett (LB) technique onto solid substrates offers an interesting route for generation of functionalized patterns by self-assembly over large surface areas. In the present paper, we discuss LB transfer of mixed LB films containing different functional amphiphiles (an azide, an estrone derivate, a lithocholic acid derivative, or an alkoxyamine) in combination with dipalmitoylphosphatidyl choline (DPPC). The effect of the mixing ratio on pattern formation is discussed, and we provide some general design rules for the synthesis of functional molecules to be applicable for the multicomponent LB transfer process. We show that these functional compounds can be successfully transferred to oxidized Si wafers in stripe pattern. Covalent attachment of the functional entities is easily achieved, and the patterned surfaces are then ready for further chemical manipulation. This is demonstrated by site-specifically covalent attaching dye molecules applying the copper(l)-catalyzed alkyne azide click reaction (CuAAC), the thiol-ene reaction, and a surface-initiated radical polymerization.

Structural Characterization of a Mixed Langmuir−Blodgett Film of a Merocyanine Dye Derivative−Deuterated Arachidic Acid Binary System and the Influence of Successive Hydrothermal Treatment in the Liquid Phase on the Film as Investigated by Polarized UV−Visible and IR Absorption Spectroscopy

We have investigated the structure of the mixed Langmuir-Blodgett (LB) film of a merocyanine dye derivative (MO(18))-deuterated arachidic acid (C(20)-d) binary system and the influence of successive hydrothermal treatment in the liquid phase (HTTL) on the mixed LB film by means of polarized UV-visible and IR absorption spectroscopy. The visible absorption band with in-plane anisotropy at 503 nm before HTTL transforms into an absorption band with in-plane isotropy at 557 nm after HTTL for 16-18 min through a peak maximum near 520 nm after HTTL for 2-12 min. The degree of total MO(18) intramolecular charge transfer for the 503 nm band is the largest among those for all of the bands. Therefore, the 503 nm band is ascribed to the MO(18) H-like aggregation, based on its shape, peak height, and in-plane anisotropy, the subsequent change to two kinds of visible peaks by successive HTTL, and the most degree of MO(18) intramolecular charge transfer among all of the aggregation states. While the MO(18) hydrocarbon chain takes the all-trans conformation before HTTL, its conformation and orientation are most disarranged after HTTL for 2 min. Subsequently, the original conformation and orientation are recovered by degrees with successive HTTL, except after final HTTL for 18 min, when the orientation is again changed. On the other hand, the C(20)-d hydrocarbon chain maintains the all-trans conformation before and after HTTL. The orientation of the C(20)-d hydrocarbon chain after HTTL for 2 min is more ordered than that before HTTL, with the nature of the C(20)-d subcell packing changing from hexagonal to orthorhombic. During successive HTTL from 2 to 18 min, the C(20)-d orientation is gradually disorganized but with the orthorhombic nature remaining constant. Thus, the variations in the conformation and orientation of the MS(18) hydrocarbon chain and in the orientation of the C(20)-d hydrocarbon chain tend to change from ordered and disordered structures and turn to more disordered and ordered ones, respectively, where the former is mainly caused by the priority action of thermal energy and the latter by hydrophobic effect due to the presence of warm water. Consequently, it is suggested that there is a correlation between the degree of structural order for both hydrocarbon chains and the preferential action that takes place during HTTL.

Enzyme Activity of Catalase Immobilized in Langmuir−Blodgett Films of Phospholipids

A major challenge for producing low cost biosensors based on nanostructured films with control of molecular architectures is to preserve the catalytic activity of the immobilized biomolecules. In this study, we show that catalase (HRP) keeps its activity if immobilized in Langmuir-Blodgett (LB) films of dipalmitoyl phosphatidylglycerol (DPPG). The incorporation of catalase into a DPPG monolayer at the air-water interface was demonstrated with surface pressure and surface potential isotherms, in addition to polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). According to the PM-IRRAS data, catalase was not denatured upon adsorption on a preformed DPPG monolayer and could be transferred onto a solid substrate. The catalytic activity of catalase in a mixed LB film with DPPG was ca. 13% higher than in solution. The control of molecular architecture and choice of a suitable phospholipid matrix allows catalase-containing LB films to be used in sensing hydrogen peroxide.

Excitation energy transfer rate from Langmuir Blodgett (LB) dye monolayers to silicon: Effect of aggregate formation

Time-resolved emission spectra (TRES) and decay curves have been recorded from mixed LB oxacarbocyanine dye monolayers and stearic acid at different distances to the silicon surface. We observe interlayer energy transfer between monomers and dimers present in the monolayer competing directly with energy transfer to silicon at close distances. We resolve these competing processes by studying the TRES spectra and decompose them into their emission components. We found the energy transfer rate for the monomer to silicon to be double than that of the dimer at a distance of d ∼ 5 nm to the silicon surface. The Förster radius for the energy transfer to silicon was estimated at 5.5 ± 0.5 nm.

Molecular-level interactions of an azopolymer and poly(dodecylmethacrylate) in mixed Langmuir and Langmuir–Blodgett films for optical storage

The applicability of azopolymers in optical storage can be extended through the use of nanostructured films produced with the Langmuir–Blodgett (LB) technique, but the film properties need to be optimized since these polymers generally do not form stable Langmuir films to be transferred onto solid substrates. Here, photoinduced birefringence was investigated for mixed Langmuir–Blodgett films from the homopolymers 4-[ N-ethyl- N-(2-methacryloxyethyl)]-4′-nitroazobenzene (HPDR1-MA) and poly(dodecylmethacrylate) (HPDod-MA). The interactions between these polymers were studied in Langmuir and LB films. Surface pressure–area isotherms pointed to molecular-level interactions for proportions of 51 mf%, 41 mf% and 31 mf% of HPDR1-MA. Phase segregation was not apparent in the BAM images, in which the morphology of the blend film was clearly different from that of the Langmuir films of neat homopolymers. Through PM-IRRAS, we noted that the interaction between the azopolymer and HPDod-MA affected the orientation of carbonyl groups. Strong interactions for the mixture with 41 mf% of poly(dodecylmethacrylate) led to stable Langmuir films that were transferred onto solid supports as LB films. The photoinduced birefringence of 101-layer mixed LB films show features that make these films useful for optical storage, with the advantage of short writing times in comparison to other azopolymer films.

Detection of catechol using mixed Langmuir–Blodgett films of a phospholipid and phthalocyanines as voltammetric sensors

The combination of metallic phthalocyanines (MPcs) and biomolecules has been explored in the literature either as mimetic systems to investigate molecular interactions or as supporting layers to immobilize biomolecules. Here, Langmuir-Blodgett (LB) films containing the phospholipid dimyristoyl phosphatidic acid (DMPA) mixed either with iron phthalocyanine (FePc) or with lutetium bisphthalocyanine (LuPc(2)) were applied as ITO modified-electrodes in the detection of catechol using cyclic voltammetry. The mixed Langmuir films of FePc + DMPA and LuPc(2) + DMPA displayed surface-pressure isotherms with no evidence of molecular-level interactions. The Fourier Transform Infrared (FTIR) spectra of the multilayer LB films confirmed the lack of interaction between the components. The DMPA and the FePc molecules were found to be oriented perpendicularly to the substrate, while LuPc(2) molecules were randomly organized. The phospholipid matrix induced a remarkable electrocatalytic effect on the phthalocyanines; as a result the mixed LB films deposited on ITO could be used to detect catechol with detection limits of 4.30 × 10(-7) and 3.34 × 10(-7) M for FePc + DMPA and LuPc(2) + DMPA, respectively. Results from kinetics experiments revealed that ion diffusion dominated the response of the modified electrodes. The sensitivity was comparable to that of other non-enzymatic sensors, which is sufficient to detect catechol in the food industry. The higher stability of the electrochemical response of the LB films and the ability to control the molecular architecture are promising for further studies with incorporation of biomolecules.

Supported Lipid Bilayers on Skeletonized Zirconium Phosphonate Surfaces For the Study of Transmembrane Proteins

Supported lipid bilayers that can fully represent biological cell membranes are attractive biomimetic models for biophysical and biomedical applications. In previous work, we developed a new approach to engineer stable supported lipid membranes. This system uses the zirconium phosphonate substrate as a reactive surface that tethers the lipid membrane via a highly covalent bond between surface zirconium ions and divalent phosphate groups in the lipid assembly. An advantage of this approach is that the zirconium phosphonate can be applied to any surfaces (gold, glass, silicon) allowing different analytical techniques to be used on the same system. However, the covalent interaction between the zirconium phosphonate film and the inner lipid monolayer that is responsible for the bilayer stability restricts membrane components such as transmembrane proteins from penetrating into the membrane and retaining their mobility. In contrast to other approaches that incorporate pillars to support the bilayers, our strategy involves the creation of reservoirs beneath the supported lipid bilayers to accomodate transmembrane proteins. Skeletonized zirconium phosphonate surfaces have been designed using the Langmuir-Blodgett (LB) technique. Sizes of the nanometer-holes were varied by controlling the amount of octadecylphosphonic acid in mixed LB layers and characterized by atomic force microscopy. The skeletonization of the film was optimized so the hollow spaces were large enough to incorporate the proteins but small enough for the membrane to bridge the spaces. The efficiency of this system as a support for transmembrane proteins has been characterized by surface plasmon resonance enhanced ellipsometry (SPREE) using the proteins Annexin V and the maxi-K ion channel to demonstrate the utility of the system as a functional cell membrane. This concept is innovative in the area of bilayer platforms and can be used with membrane and transmembrane proteins.

Mixing Alternating Copolymers Containing Fluorenyl Groups with Phospholipids to Obtain Langmuir and Langmuir−Blodgett Films

The control of molecular architectures may be essential to optimize materials properties for producing luminescent devices from polymers, especially in the blue region of the spectrum. In this Article, we report on the fabrication of Langmuir-Blodgett (LB) films of polyfluorene copolymers mixed with the phospholipid dimyristoyl phosphatidic acid (DMPA). The copolymers poly(9,9-dioctylfluorene)-co-phenylene (copolymer 1) and poly(9,9-dioctylfluorene)-co-quaterphenylene) (copolymer 2) were synthesized via Suzuki reaction. Copolymer 1 could not form a monolayer on its own, but it yielded stable films when mixed with DMPA. In contrast, Langmuir monolayers could be formed from either the neat copolymer 2 or when mixed with DMPA. The surface pressure and surface potential measurements, in addition to Brewster angle microscopy, indicated that DMPA provided a suitable matrix for copolymer 1 to form a stable Langmuir film, amenable to transfer as LB films, while enhancing the ability of copolymer 2 to form LB films with enhanced emission, as indicated by fluorescence spectroscopy. Because a high emission was obtained with the mixed LB films and since the molecular-level interactions between the film components can be tuned by changing the experimental conditions to allow for further optimization, one may envisage applications of these films in optical devices such as organic light-emitting diodes (OLEDs).

Patterning of J-aggregated dyes using directed self-assembly on micro- and nanopatterned templates fabricated from phase-separated mixed Langmuir–Blodgett films

We report a useful technique for the deposition of dyes in the form of J-aggregates using directed self-assembly on the micro- and nanopatterned templates fabricated from the phase-separated mixed Langmuir–Blodgett (LB) films. The patterns of the mixed LB films can be tuned by adjusting the intermolecular interactions between the film-forming molecules. We used the mixed LB films containing silane coupling agent for the fabrication of micro- and nanopatterned templates, taking advantage of the difference between the surface free energy of the patterned regions and that of the self-assembled monolayers of the silane coupling agent. Atomic force microscopy showed that dyes were deposited by casting, spin-coating and the LB technique in accordance with the patterns of the original mixed LB films. Emission spectroscopy revealed that J-aggregates were formed in the patterned films. We succeeded in obtaining nanopatterns of a cyanine dye in the form of J-aggregates on the templates.

Self-assembled arrays of silica particles on the patterns reflecting the phase-separated structures of mixed Langmuir–Blodgett films

In this study, we constructed self-assembled arrays of silica particles on the micro- and nanopatterns of functionalized templates fabricated from phase-separated mixed Langmuir–Blodgett (LB) films. Electrostatic interaction between the carboxylic groups of silica particles and amino groups on the functionalized templates results in the formation of the self-assembled arrays of silica particles. The patterns of the silica particle arrays can be designed by controlling the phase-separated structures of the original mixed LB films.

Directed self-assembly of gold nanoparticles and gold thin films on micro- and nanopatterned templates fabricated from mixed phase-separated Langmuir-Blodgett films

We report a useful technique to immobilize Au nanoparticles (Au-NPs), double layers of Au-NPs and Au thin films on micro- and nanopatterns using directed self-assembly on templates fabricated from phase-separated mixed Langmuir-Blodgett (LB) films. The patterns of the mixed LB films can be tuned by adjusting the intermolecular interactions between the film-forming molecules and the fabrication conditions of the films. We used mixed LB films containing a silane coupling agent for the fabrication of micro- and nanopatterned templates to immobilize Au-NPs of different sizes in the patterned regions. Atomic force microscopy, Auger electron spectroscopy and scanning Auger electron mapping of the Au-NP-immobilized films showed that Au-NPs were immobilized in accordance with the patterns of the original mixed LB films. A layer of the immobilized Au-NPs was used as a catalyst for the succeeding Au electroless deposition or as a first layer for the stacking of a second layer using the layer-by-layer deposition method. We have also succeeded in controlling the thickness and density of the Au-NPs.

J-Aggregation Characteristics of Merocyanine Dye with Arachidic Acid LB Films by Heat Treatment

For a measurement of J-aggregation characteristics by heat treatment, we fabricated arachidic acid (AA)-Merocyanine dye mixed Langmuir-Blodgett (LB) films. pi-A curves were used to investigate the surface pressure of the LB film from a liquid to a solid state while the pressure ranged from 35 and 40 mN/m. When the surface pressure reached 40 mN/m, a monolayer was deposited onto the hydrophilic glass substrates by Y-type deposition. For the UV spectrum observation, a multi layer film was deposited. A narrowing of the red-shifted band was observed. We studied the effect of heat treatments at temperatures below 60 degrees C by observing the UV spectra of merocyanine dye (MD). The J-aggregation was centered at 550-590 nm at 20 degrees C-25 degrees C. We will study the system before and after the application of heat treatment J-aggregation. The J-aggregation will be thermally induced in the mixed LB films by heat treatments at various temperatures. We expect that after heat treatment, the spectral shape and peak of the band will be altered. We investigated that morphology of MD using STM. Also I-V curve was decreased as increasing temperatures.

Synthesis of azopolymers with controlled structure and photoinduced birefringence in their LB films

The molecular architecture of azopolymers may be controlled via chemical synthesis and with selection of a suitable film-forming method, which is important for improving their properties for practical uses. Here we address the main challenge of combining the photoinduced birefringence features of azopolymers with the higher thermal and mechanical stabilities of poly(methyl methacrylate) (PMMA) using Atom Transfer Radical Polymerization (ATRP) to synthesize diblock- and triblock-copolymers of an azomonomer and the monomer methyl methacrylate. Langmuir–Blodgett (LB) films made with the copolymers mixed with cadmium stearate displayed essentially the same optically induced birefringence characteristics, in terms of maximum and residual birefringence and time for writing, as the mixed LB films with the homopolymer poly[4-(N-ethyl-N-(2-methacryloxyethyl))amino-2′-chloro-4′-nitroazobenzene] (HPDR13), also synthesized via ATRP. In fact, the controlled architecture of HPDR13 chains led to Langmuir films that could be more closely packed and reach higher collapse pressures than the corresponding films obtained with HPDR13-conv synthesized via conventional radicalar polymerization. This allowed LB films to be fabricated from neat HPDR13, which was not possible with HPDR13-conv. The enhanced organization in the LB films produced with controlled azopolymer chains, however, led to a smaller free volume available for isomerization of the azochromophores, thus yielding a lower photoinduced birefringence than in the HPDR13-conv films. The combination of ATRP synthesis and LB technology is then promising to obtain optical storage in films with improved thermal and mechanical processabilities, though a further degree of control must be sought to exploit film organization while maintaining the necessary free volume in the films.

Phase-Separated Structures of Mixed Langmuir−Blodgett Films of Fatty Acid and Hybrid Carboxylic Acid

Phase separation often occurs in mixed Langmuir-Blodgett (LB) films. Usually circular domains at the micrometer length scale form in the LB films. The size and shape of the domains are governed by a compromise between two competing interactions of line tension and dipole-dipole interaction. An attempt was made to control the line tension by varying systematically the hydrophobic moieties of the film-forming molecules. Phase-separated structures of two-component mixed LB films of fatty acid [C(k)H(2k+1)COOH (HkA)] and hybrid carboxylic acid [C(m)F(2m+1)C(n)H(2n)COOH (FmHnA)] were investigated. IR spectra of the mixed LB films of H17A and F8H10A revealed that the alkyl chains were in an all-trans conformation and that the molecular orientation remained unchanged when the two components were mixed. Nanowires formed in the mixed LB films of HkA and F8H10A. The width of the nanowires increased with an increase in k. Domain size and shape in the mixed LB films of H17A and FmHnA depended strongly on the values of m and n. Circular domains at the micrometer length scale formed in the region m + n < 16. In contrast, domains at the nanometer length scale formed in the region m + n > or = 16 except for F6H10A. These results were explained by using a lattice model that considers the effect of the hydrophobic moieties of fatty acid and hybrid carboxylic acid on the line tension.

Thermal Behavior of H-Aggregate in a Mixed Langmuir−Blodgett Film of Merocyanine Dye, Arachidic Acid, and n-octadecane Ternary System Investigated by UV−visible and IR Absorption Spectroscopy

We have investigated the thermal behavior of H-aggregate in a mixed Langmuir-Blodgett (LB) film of the merocyanine dye (MS18)-arachidic acid (C20)- n-octadecane (AL18) ternary system by means of UV-visible and IR absorption spectroscopy in the range from 25 to 250 degrees C with a continuous scan. The results of both UV-visible and IR spectra indicate that the temperature-dependent variation in MS 18 aggregation state is linked not only with the degree of intramolecular charge transfer and the behavior of packing, orientation, conformation, and thermal mobility of the MS18 hydrocarbon chain but also with the presence and absence of AL18. The H-aggregate dissociates from 25 up to 50 degrees C, which is caused by the AL18 evaporation from the mixed LB film and the increment of thermal mobility of the MS18 hydrocarbon chain. From 110 to 160 degrees C, blue-shifted bands, attributed to the oligomeric MS18 aggregation, appear near 515 nm in the MS18-C 20-AL18 ternary system as well. The temperature at which the 515 nm band occurs is identical for both present ternary system and previously investigated MS18-deuterated arachidic acid (C20- d) binary system, and it is in good agreement with the melting point (110 degrees C) of cadmium arachidate (CdC20). Therefore, it is indicated that the driving force which induces the 515 nm band comes from the melting phenomenon of CdC20 molecules which are phase-separated from MS 18 molecules in as-deposited LB films.

Micro- and Nanopatterned Copper Structures Using Directed Self-Assembly on Templates Fabricated from Phase-Separated Mixed Langmuir−Blodgett Films

We report a versatile method to confine metal thin films in micro- and nanopatterns using directed self-assembly on the templates fabricated from phase-separated mixed Langmuir-Blodgett (LB) films. The pattern of the mixed LB films can be tuned by adjusting intermolecular interaction between the film-forming molecules in the LB films and by varying the fabrication conditions of the films such as the mixing ratio, subphase temperature, and surface pressure. We use the patterned LB films for templates to confine metal in patterned regions, taking advantage of the difference between the surface free energy of the patterned regions and that of the self-assembled monolayer of the silane coupling agent. Au nanoparticles are confined onto the patterned films as a catalyst for the succeeding Cu electroless deposition. The atomic force microscopic images, Auger electron spectra, and scanning Auger electron maps of a Cu-deposited film show that Cu is selectively deposited on the patterns of phase separation of the original mixed LB films.

Aggregation Behavior of Homo‐PS/PS‐b‐P2VP Blends at the Air/Water Interface

AbstractThe mixed Langmuir monolayers and Langmuir–Blodgett (LB) films of homo‐polystyrene (h‐PS) and the diblock copolymer polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP) have been characterized by the Langmuir monolayer technique and tapping mode atomic force microscopy (AFM), respectively. When the content of h‐PS is below 80 wt.‐%, the mixed LB films of h‐PS/PS‐b‐P2VP mainly exhibit isolated circular nanoaggregates. With a further increase of the h‐PS content (80–95%), however, highly uniform and stable necklace‐network structures are observed in the mixed LB films.magnified image